Effects of Uniform Heat Flux and Velocity-Slip Conditions at Interface on Heat Transfer Phenomena of Smooth Spheres in Newtonian Fluids

The effects of the uniform heat flux and a linear velocity-slip on the heat transfer phenomena of spheres in Newtonian fluids are numerically investigated using semi-implicit marker and cell (SMAC) method implemented on a staggered grid arrangement in spherical coordinates. The solver is thoroughly benchmarked through domain independence, grid independence, and comparison with literature. Further extensive results are obtained in the range of conditions as: Reynolds number, Re = 0.1–200; Prandtl number, Pr = 1–100; and dimensionless slip number, λ = 0.01–100. The results are presented and discussed such that the isotherm contours and the local and average Nusselt numbers of isoflux spheres with velocity-slip at the interface are compared with their isothermal spheres counterparts under identical conditions. Briefly, the results indicate that the average Nusselt numbers of isoflux spheres are large compared to those of isothermal spheres under identical conditions. Finally, an empirical correlation is developed for the average Nusselt numbers of the spheres in Newtonian fluids with velocity-slip and the uniform heat flux conditions along the fluid–solid sphere interface.

A NUMERICAL MODEL FOR WAVE PROPAGATION OVER MUDDY SLOPE

A numerical model for the interaction between waves and muddy seabed is developed, in which the motion of the movable mud and the motion of water are solved simultaneously. The governing equations for both water and the mud are the continuity equation and the equations of motion for incompressible fluids. Water is treated as a Newtonian fluid, while a visco-elastic-plastic model is used to describe the rheology of the mud. Both the interface between water and the mud and the free water surface are traced by the VOF (Volume of Fluid) method. The numerical method is based on the well-known SMAC method. The numerical model is applied to simulate wave propagation over a muddy slope, and the numerical results are in reasonable agreement with the experimental data. The present model is proved better performance than the traditional analytic model in case that topography change is not negligible.

A Very Simple Immersed Boundary Method Applied to Three-Dimensional Incompressible Navier-Stokes Solvers Using Staggered Grid

A very simple computational algorithm for solving flows over complex geometries is presented. This algorithm is based on a kind of the Immersed Boundary (IB) Methods. The complex 3D geometries are generated by the 3DCG software as a surface mesh of triangle polygons. A 3D Cartesian grid is used for the flow field. Only the points stuck with grid lines on triangle polygons are detected and flow velocities are modified using the points with the IB method. In this paper, this approach is applied to an incompressible Navier-Stokes solver based on the Simplified Marker and Cell (SMAC) method. Some practical flow problems assuming low Reynolds number are calculated and the results are compared with the experimental and the numerical results.

LES of Turbulent Separated and Reattached Flow Around a Surface-Mounted Plate

LES method is applied to simulate numerically a turbulent separated and reattached flow around a surface-mounted plate. Smagorinsky model is used in the analysis and fundamental equations are discretized by means of the finite volume method, and their resulting finite difference equations are solved using SMAC method. The calculations are conducted for Re = 105. It is found that the present numerical results, in general, agree well with the previous experimental ones. The complicated vortical flow structures around the plate and their time variations are visualized through various fields of flow quantities.

Repeatability of the Petrifilm™ HEC Test and Agreement with a Hydrophobic Grid Membrane Filtration Method for the Enumeration of Escherichia coli O157:H7 on Beef Carcasses

The Petrifilm™ HEC test (3M Canada Inc., London, Ontario), a quantitative microbiological test for Escherichia coli O157:H7, was evaluated for its performance as a beef-carcass monitoring test. Test repeatability and agreement with an E. coli O157:H7 detection method using a hydrophobic grid membrane filter (HGMF) overlaid onto cefixime–tellurite–sorbitol MacConkey agar (CT-SMAC) followed by a latex agglutination test for the O157 antigen were determined by using pure cultures of E. coli O157:H7, beef samples experimentally contaminated with bovine feces containing E. coli O157:H7, and naturally contaminated beef carcasses of unknown E. coli O157:H7 status from a local abattoir. The Petrifilm™ HEC test showed excellent repeatability and excellent agreement with the HGMF–CT-SMAC method when test samples were obtained from pure cultures and experimentally contaminated meat. All 125 naturally contaminated beef carcasses surveyed were negative for E. coli O157:H7 with both microbial methods. The Petrifilm™ HEC test, however, demonstrated a significantly lower proportion of cross-reactive organisms (false-positive reactions) than the HGMF–CT-SMAC method. Given the performance of this test coupled with its ease of use and compact size, it shows considerable promise for carcass testing where abattoir laboratory facilities are limited and as a substitute for more complex laboratory testing methods used in established laboratories.

A Successive Merging and Condensation (SMAC) Method Applied to Transient Analysis of Multi-Shaft Rotor System

A method for performing transient dynamic analysis of multi-shaft rotor system is proposed. The proposed methodology uses the reported Successive Merge and Condensation (SMAC) method [12] and a decoupling technique to decouple the shafts. Multi-shaft rotor systems are treated as systems of many independent single shaft rotor systems with external unknown coupling forces acting at the points of couplings. For each time step, first, the SMAC method is used to get the transient response in terms of the unknown coupling forces. This is followed by the application of the coupling constraints to calculate the coupling forces and, in turn, the response at the end of that time step. The proposed method preserves the efficiency advantages of the SMAC algorithm for single-shaft rotor system. Numerical examples to validate and illustrate the applicability of the method are given. The method is shown to be applicable to linear and non-linear coupling problems.